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AMES, Iowa - The scientific and technological literature is
abuzz with nanotechnology and its manufacturing and medical
applications. But it is in an area with a less glitzy
aura-plant sciences-where nanotechnology advancements are
contributing dramatically to agriculture.

Researchers at Iowa State University have now demonstrated the
ability to deliver proteins and DNA into plant cells,
simultaneously. This is important because it now opens up
opportunities for more sophisticated and targeted plant genome
editing-techniques that require the precise delivery of both
protein and DNA to bring about specific gene modifications in
crop plants. Such modifications are becoming more and more
important in the face of our changing climates as new insect
pests, plant diseases and soil stresses emerge where previously
there were few.

While DNA delivery into cells has become routine, delivering
proteins and enzymes to both animal and plant cells has proved
more challenging. The Iowa State team's protein delivery
advancement is an important achievement toward this end.

The Iowa State research team includes Kan Wang, professor of
agronomy; Brian
Trewyn, associate scientist in chemistry; Susana
Martin-Ortigosa, a post-doctoral research associate in
agronomy; and Justin Valenstein, a chemistry doctoral student.

Nanoparticles are tiny materials that are the size equivalent
of several molecules sitting side-by-side or the size of a big
virus. A single nanometer is one-billionth of a meter. The
virus that causes AIDS is roughly 100 nanometers in diameter.

Using new and improved custom-built honeycomb-like mesoporous
silica nanoparticles that the Iowa State team designed five
years ago, the researchers have demonstrated co-delivery of
functional protein and DNA into plant cells.

The first generation of these customized particles were
relatively small (100 nanometers) and so the available packing
spaces were unable to accommodate larger functional molecules
such as proteins or enzymes. This next generation is five times
the size (500 nanometers) and looks something like an
ultra-fine piece of Honeycomb cereal.

The key to the researchers' success is a newly devised
method for making larger uniform pouches in the custom
nanoparticles. An additional modification-gold plating the
entire silica particle prior to packing-improved DNA and
protein binding for a more secure payload.

To test the new particle's effectiveness, Wang and her
colleagues loaded the pores with a green florescent protein
derived from jelly fish, which serves as a photo marker inside
the plant cell. Next, these particles were coated with DNA
encoding a red protein from coral. The complex was then shot
into plant cells using a gene gun, a traditional gene delivery
method that gets foreign material past the plant's
protective cell wall.

The gold plating innovation added some greatly needed ballistic
heft to the particles, ensuring their ability to cannonball
through the plant cell wall once released from the gene gun.

Cells that fluoresce both red and green at the same time
confirm successful delivery. The team has demonstrated success
in onion, tobacco and maize cells.

The work is a tangible realization of efforts the team had in
the design stage just two years ago when colleague Victor
Lin of Iowa State University and the U.S. Department of
Energy's Ames
Laboratory unexpectedly died. "He was such a brilliant
scientist," says Wang. "We all felt completely lost
when we lost him."

But the team pulled together, capitalizing on the excellent
training all had received from working with Lin to make this
next generation particle a reality.

"We would have been unable to work out anything without
each other," says Wang. "This success proves his
legacy continues."

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Quick Look

Iowa State University researchers are using nanoparticles
originally developed by the late Victor Lin to simultaneously
deliver proteins and DNA into plant cells. The technology could
allow more sophisticated and targeted editing of plant genomes.
And that could help researchers develop crops that adapt to
changing climates and resist pests. The discovery has been
published online by the journal Advanced Functional Materials.

Quote

"He was such a brilliant scientist. We all felt completely
lost when we lost him. We would have been unable to work out
anything without each other. This success proves his legacy
continues."